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Esterhuizen L.L.,University of Johannesburg | Mabasa K.G.,ARC Vegetable and Ornamental Plant Institute | Mabasa K.G.,University of Witwatersrand | Van Heerden S.W.,Sakata Vegenetics RSA Pty Ltd | And 5 more authors.
Journal of Applied Entomology | Year: 2013

The whitefly Bemisia tabaci cryptic species complex contains some important agricultural pest and virus vectors. Members of the complex have become serious pests in South Africa (SA) because of their feeding habit and their ability to transmit begomovirus species. Despite their economic importance, studies on the biology and distribution of B. tabaci in SA are limited. To this end, a survey was made to investigate the diversity and distribution of B. tabaci cryptic species in eight geographical locations (provinces) in SA, between 2002 and 2009, using the mitochondrial cytochrome oxidase I (mtCOI) sequences. Phylogenetic analysis revealed the presence of members from two endemic sub-Saharan Africa (SSAF) subclades coexisting with two introduced putative species. The SSAF-1 subclade includes cassava host-adapted B. tabaci populations, whereas the whiteflies collected from cassava and non-cassava hosts formed a distinct subclade, referred to as SSAF-5, and represent a new subclade among previously recognized southern Africa clades. Two introduced cryptic species, belonging to the Mediterranean and Middle East-Asia minor 1 clades, were identified and include the B and Q types. The B type showed the widest distribution, being present in five of the eight provinces explored in SA, infesting several host plants and predominating over the indigenous haplotypes. This is the first report of the occurrence of the exotic Q type in SA alongside the more widely distributed B type. Furthermore, mtCOI PCR-RFLP was developed for the SA context to allow rapid discrimination between the B, Q and SSAF putative species. The capacity to manage pests and disease effectively relies on knowledge of the identity of the agents causing the damage. Therefore, this study contributes to the understanding of South African B. tabaci species diversity, information needed for the development of knowledge-based disease management practices. © 2012 Blackwell Verlag, GmbH.


Lewu M.N.,University Of Fort Hare | Yakubu T.M.,University Of Ilorin | Adebola P.O.,ARC Vegetable and Ornamental Plant Institute | Afolayan A.J.,University Of Fort Hare
Journal of Medicinal Food | Year: 2011

The growth performance of weanling albino rats (Rattus norvegicus) maintained on different accessions (offspring of a variety that was planted/collected at a specific location and time but differing in certain morphologic characteristics) of cooked Colocasia esculenta (cocoyam)-based diets (UFCe1-UFCe7) for 28 days was investigated. Proximate analysis of the formulated diets revealed that UFCe3, UFCe4, UFCe5, UFCe6, and UFCe7 had significantly (P<.05) higher moisture contents than the corn starch-based diet (control). All the accession-based diets of C. esculenta had higher ash contents. Similarly, all the accessions of the C. esculenta-based diet had lower crude lipid content, whereas UFCe3-UFCe7 had significantly lower protein content. Although the crude fiber content was significantly higher in UFCe2, UFCe4, and UFCe5, only UFCe3 had significantly higher carbohydrate content among all the accessions of C. esculenta-based diets. UFCe1, UFCe2, UFCe4, UFCe5, and UFCe6 increased the average weekly water intake, feed consumption, total body weight, liver-body weight ratio, and kidney-body weight ratio of the animals; UFCe3 and UFCe7 decreased these measures. Overall, UFCe1, UFCe2, UFCe4, UFCe5, and UFCe6 are recommended as diets with promise to enhance growth performance in the animals. © Copyright 2011, Mary Ann Liebert, Inc.


Lewu M.N.,University Of Fort Hare | Yakubu M.T.,University Of Ilorin | Adebola P.O.,ARC Vegetable and Ornamental Plant Institute | Afolayan A.J.,University Of Fort Hare
Journal of Medicinal Food | Year: 2010

The liver and kidney functional indices of weanling albino rats (Rattus norvegicus) maintained on different accessions (offspring of a variety planted/collected at a specific location and time but differing in certain morphological characteristics) of cooked Colocasia esculenta (cocoyam)-based diets (UFCe1-UFCe7) for 28 days were investigated. All the accessions of C. esculenta-based diets did not significantly (P >.05) alter the serum levels of albumin, globulin, inorganic phosphorus, calcium, magnesium, and uric acid of the animals.The total protein and total bilirubin levels decreased only in the UFCe3-and UFCe4-fed animals, respectively. Whereas UFCe1 and UFCe2 significantly decreased the conjugated bilirubin levels, UFCe3 and UFCe6 increased it. While all the accessions of C. esculenta-based diet decreased the serum alkaline phosphatase activity, γ-glutamyl transferase activity was increased. UFCe1 and UFCe5 increased the serum alanine aminotransferase activity, whereas UFCe4 decreased the activity of the enzyme. Again, UFCe3 and UFCe1 increased the serum creatinine and aspartate aminotransferase activity of the animals. Furthermore, the computed blood urea nitrogen:creatinine ratio was higher in animals maintained on UFCe1-, UFCe3-, UFCe4-, and UFCe5-based diets. Whereas UFCe6 and UFCe7 increased the level of sodium in the serum of the animals, UFCe4 and UFCe5 decreased the chloride level. The serum urea level was decreased by UFCe1, UFCe3, UFCe4, and UFCe5, whereas the potassium level increased in the UFCe4-, UFCe6-, and UFCe7-fed animals. Overall, the results revealed that all the accessions of C. esculenta produced selective effects on the hepatic and renal functional indices of the weanling rats. The highest alterations were produced by UFCe4, whereas the least was from UFCe2. These alterations may have consequential effects on the normal functioning of the liver and kidney of the animals. UFCe2 exhibited the least toxicity risk among the accessions of C. esculenta growing in the KwaZulu-Natal Province of South Africa. © 2010, Mary Ann Liebert, Inc. and Korean Society of Food Science and Nutrition.


Lewu M.N.,University Of Fort Hare | Adebola P.O.,ARC Vegetable and Ornamental Plant Institute | Afolayan A.J.,University Of Fort Hare
Journal of Food Composition and Analysis | Year: 2010

Colocasia esculenta (L.) Schott (cocoyam) is cultivated primarily for its edible tubers. The effect of cooking the tubers on the mineral and antinutrient compositions of seven accessions (UFCe1-UFCe7) of the crop growing in South Africa was investigated. Analysis of mineral elements showed a general decrease in the mean values of cooked samples, especially phosphorus, calcium, potassium and zinc. Manganese was not detected in all the accessions studied, while iron was sparingly detected in cooked accessions UFCe2, UFCe3 and UFCe5. Potassium and magnesium contents were reasonably high. The results further portray the accessions as good sources of potassium, magnesium, sodium and calcium, whose salts regulate the acid-base balance of the body. Boiling markedly reduced the level of the anti-nutritional factors, thereby improving the food quality. © 2010 Elsevier Inc.


Lewu M.N.,University Of Fort Hare | Adebola P.O.,ARC Vegetable and Ornamental Plant Institute | Afolayan A.J.,University Of Fort Hare
Journal of Food Quality | Year: 2010

Potato (Solanum tuberosum. ) is a popular staple food in South Africa, whereas cocoyam (Colocasia esculenta. ) remains unpopular and not well known outside KwaZulu-Natal Province, where it is cultivated mainly for subsistence. A comparative study of the nutritional compositions of commercially available tubers of both crops in South Africa was carried out. The results showed that the tubers of the two crops were high in carbohydrate and energy but low in lipid contents. Although potato was significantly higher in moisture and ash than the tubers of cocoyam, carbohydrate, caloric and crude protein contents were not significantly different (P < 0.05) in both tubers. Whereas boiling improved the availability of crude protein, fiber and lipid contents for both species, boiling reduced the ash contents in the tubers of both crops. Manganese levels were not detectable, whereas iron contents were appreciably high, but magnesium and copper contents were in the average range in both tubers. Whereas cooking reduced iron level in potato (11.20-9.95 mg/100 g DM), a significant increase in iron was observed for cocoyam (9.08-13.87 mg/100 g DM). Cooking significantly lowered magnesium, potassium and copper contents in both crops. Oxalates and phytate contents were significantly higher in cocoyam when compared with potato. Cooking remarkably reduced the anti-nutrient contents of both tubers. © 2010 Wiley Periodicals, Inc.

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